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Claims  |
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It is claimed and desired to secure by Letters Patent:
1. Apparatus for the controllable placement of a sticker on the top of a
course of lumber comprising:
releasable sticker-face capture means including at least one pivotable
support arm for supporting a face of the sticker, and releasable sticker
retaining means operable with said support arm positively to capture the
sticker by pressing against an opposite face thereof, thereby pinching the
sticker;
generally vertically reciprocable carriage means mounting the capture means
operable alternately to lower the capture means to the top of the lumber
course and to raise the capture means therefrom, the carriage means
including lost motion means providing a predefined dwell time after the
lowering and before the raising of the carriage means; and
sticker release means operable during the dwell time to pivot the support
arm out from under the sticker, thereby releasing the sticker
substantially at the level of the lumber course.
2. The apparatus of claim 1, wherein the retaining means tensionably
impinge upon the top of the sticker, thereby urging the sticker downwardly
through the controlled descent and the dwell time.
3. The apparatus of claim 1, wherein the sticker release means is operable
by spring tension.
4. The apparatus of claim 1, wherein the capture means further includes a
rocker arm pivotable with the support arm, the rocker arm under spring
tension normally urging the support arm into generally horizontally
position under the sticker.
5. The apparatus of claim 1, wherein the lost motion means includes stop
means mounted on the carriage means for engagement with the top of the
course of lumber, the stop means, upon such engagement, being operable to
halt the descent of the capture means and to enable the operation of the
sticker release means.
6. In apparatus for the placement of a sticker on the top of a course of
lumber, the improvement comprising;
sticker-face capture means for positively capturing the sticker throughout
the placement thereof, and a mounting for the capture means whereby it is
shiftable between a raised position and a lowered position adjacent the
level of the top of a course of lumbar the capture means including at
least one pivotable support arm for supporting transversely thereabove a
first face of the sticker, and at least one corresponding sticker retainer
capable of impinging upon an opposite face of the sticker to urge the
sticker downwardly into captured engagement with the support arm such
capture means further including means for pivoting the support arm to a
position freeing the sticker and for urging the retainer to force the
sticker downwardly with the capture means in its lowered position.
7. The improvement of claim 6, wherein the sticker retainer is pivotally
mounted and the capture means includes a spring biasing pivotal movement
of the retainer to urge the sticker downwardly.
8. An apparatus for the placement of stickers having opposite faces on the
top of a course of lumber, the apparatus having at least one placement
station, each station having vertically shiftable placement means with a
raised position for receiving consecutive stickers of a predetermined
nominal thickness and a lowered position for placing the stockers in a
predetermined generally horizontal position on the top of the course of
lumber, the improvement comprising:
feeding means for feeding consecutive stickers to said placement means with
the placement means in its raised position the feeding means including an
inclined sticker pocket with an upper inlet end and a lower outlet end,
the pocket having a plural sticker capacity and said outlet end being
adjacent said placement means with the placement means in its raised
position, the pocket having an inclined lower portion capable of slidably
receiving thereagainst stickers disposed generally lengthwise horizontally
with one face of the stickers slidably engaging the lower portion, the
pocket having an upper portion portion disposed in generally parallel,
spaced apart relationship to the lower portion at a distance substantially
greater than the predetermined nominal thickness of the stickers, the
feeding means further including releasable sticker retention means at said
outlet end released with the placement means in its raised position and
operable with the placement means out of its raised position to retain
upstream stickers within the pocket and operable to release a sticker for
placement within the placement means with the placement means in its
raised position.
9. The improvement of claim 8, wherein the releasable sticker retention
means includes a pivotable pinch bar that is capable of being urged by
spring tension into impingement with the opposite face of the to-be-placed
sticker.
10. The improvement of claim 8, wherein the sticker pocket is inclined at
an angle of substantially less than 90.degree. relative to the conveyor
means.
11. The improvement of claim 11, wherein the sticker pocket is inclined at
an angle of between 30.degree. and 60.degree. relative to the conveyor
means.
12. The improvement of claim 11, wherein the sticker pocket is inclined at
an angle of approximately 45.degree. relative to the conveyor means.
13. In apparatus for the placement of stickers on the top of a course of
lumber, the apparatus having at least one placement station, each station
being capable of placing consecutive stickers in a predetermined generally
horizontal position relative to the course of lumber, improved placement
means comprising:
capturing means for releasably positively capturing each sticker throughout
the placement of the sticker;
means for generally vertically reciprocating the capturing means; and
means for releasing the capturing means by spring tension to deposit the
sticker in the predetermined position.
14. In apparatus for the placement of plural stickers at predetermined
positions along the tops of consecutive lumber courses, the apparatus
having means at each of the predetermined positions for the controllable
placement of consecutive stickers corresponding to consecutive lumber
courses, the apparatus further having single drive means operable
simultaneously to operate the placement means at each predetermined
position, the improvement comprising:
extendable and retractable slider link means, coupled to each of the
placement means, for moving each placement means through a plurality of
placement cycles wherein each placement cycle includes extending each
placement means to a predetermined position and retracting each therefrom.
15. The improvement of claim 14, wherein the placement means at each
predetermined position includes a generally vertically reciprocable
carriage for displacing one sticker at a time from a first location to the
top of the course of lumber, further comprising carriage mounted stop
means for halting the descent of the carriage when the top of the course
of lumber is reached thereby.
16. Apparatus for the consecutive placement of stickers atop consecutive
courses of lumber, comprising:
means for receiving stickers;
means for displacing one sticker at a time from the receiving means to the
top of consecutive courses of lumber, including a trip mechanism and a
generally vertically reciprocable carriage having dual laterally spaced
apart releasable positive sticker capture means for releasably capturing
one sticker at a time, the capture means including a generally horizontal
pivotable sticker support arm, the carriage further having at least a pair
of laterally spaced apart stops for engaging a top of consecutive courses
of lumber, the displacing means further including means for alternately
extending and retracting a slider link eccentrically attached to a
pivotably carriage-mounted rocker arm, the rocker arm being pivotable with
the support arm and being urged, during the extending of the slider link
and until the stops engage the top of consecutive course of lumber, by
slider link tension into a first sticker supporting position and being
urged, during the further extending and the retracting of the slider link
and until the rocker arm engages the trip mechanism, by spring tension
into a second sticker release position.
17. The apparatus of claim 16, wherein the capture means further includes
dual laterally spaced apart releasable sticker retainers capable of
impinging upon the upper surface of the sticker generally opposite a
corresponding sticker support arm to urge the sticker downwardly into
captured engagement with the support arm until the rocker arm is urged
into the second sticker release position and thereafter to urge the
sticker downwardly onto the top of the course of lumber.
18. The apparatus of claim 16, wherein the extending-retracting means
includes generally horizontally reciprocable drive means laterally offset
from the carriage means, and wherein the slider link extends engagingly
semicircumferentially along a lockably rotatable toothed sprocket, the
sprocket being selectively lockable to prevent reciprocation of the
carriage in response to the extending and retracting of the
extending-retracting means.
19. The apparatus of claim 16 having conveyor means for conveying stickers
to the sticker receiving means and in which the stickers are of a
predetermined nomimal thickness, wherein the sticker receiving means
includes an inclined sticker pocket having a plural sticker capacity and
extending between the conveyor means and the displacing means, the pocket
being capable of slidably receiving against a lower portion thereof
stickers disposed generally lengthwise horizontally with one face slidably
engaging the lower portion, the pocket having an upper portion disposed in
generally parallel, spaced apart relationship to the lower portion at a
distance substantially greater than the predetermined nominal thickness of
the stickers, the feeding means further including releasable sticker
retention means operable with the displacement means to retain upstream
stickers within the pocket and release the to-be-placed sticker for
placement.
20. Apparatus for the placement of plural stickers at predetermined
positions along the tops of consecutive lumber courses, comprising:
placement means at each of plural predetermined positions along the course
of lumber for placing one sticker at a time in a corresponding position on
top of consecutive courses of lumber, the placement means including a trip
mechanism, a generally vertically reciprocable carriage having means for
releasably positively capturing one sticker at a time, the capturing means
including a generally horizontal pivotable sticker support arm, the
carriage further having plural stops for engaging the tops of consecutive
courses of lumber, each placement means further including means for
alternately extending and retracting a slider link eccentrically attached
at a distal end thereof to a pivotably carriage mounted rocker arm, the
rocker arm being pivotable with the support arm and being urged, during
the extending of the slider link and until at least one of the stops
engages the top of consecutive courses of lumber, by slider link tension
into a first sticker supporting position and being urged, during the
further extending and the retracting of the slider link and until the
rocker arm engages the trip mechanism, by spring tension into a second
sticker release position;
single common drive means capable of operating simultaneously the placement
means at each predetermined position;
means for feeding consecutive stickers to the placement means at each
predetermined position;
means for indexing through consecutive lumber and
means operably disassociation the placement means at at least one
predetermined position from the drive means for selectively preventing the
operation of the disassociated placement means.
21. Apparatus for placing a sticker on the top of a course of lumber
comprising:
a pocket for holding a series of stickers with the stickers disposed as a
layer of stickers disposed edge-to-edge and the pocket having an outlet
end where the terminal sticker in said layer is fed from the pocket,
capture means for capturing a terminal sticker at said outlet end of the
pocket and a mounting for said capture means whereby it is shiftable
between a raised position located adjacent said outlet end and a lowered
position located adjacent the top of the course of lumber,
said capture means including a support arm which engages a surface of the
sticker which extends on one side of the sticker normal to its edges, and
a retainer which engages a surface of the sticker which extends on the
opposite side of the sticker, said support arm being movably mounted on
said mounting for movement away from the surface of the sticker that is
engages to a release position for the support arm, said capture means
further including producing movement of said support arm to its said
release position with the capture means in its said lowered position. |
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Claims |
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Description |
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BACKGROUND AND SUMMARY OF THE INVENTION
This invention relates generally to sticker placer apparatus. More
particularly, this invention concerns improved apparatus providing
inclined sticker feed pockets, positive sticker capture throughout
placement, and a drive linkage that permits each placement arm in a system
to `seek` the level of the top of the course of lumber. The combined
features of the invention provide sticker placer apparatus achieving
accurate placement and high throughput in virtually jam-proof, fully
automatic operation.
Sticker placer apparatus are used to place stickers between stacked courses
of fresh-cut lumber. The sticker serves the purpose of stabilizing the
stacked lumber and permitting airflow between courses while the lumber
cures. Typically, sticker placer apparatus are used in conjunction with
lumber stacking equipment, wherein the lumber stacker develops a course of
lumber and then the sticker placer places stickers transversely therealong
above which the lumber stacker develops another course, etc. The number of
sticker placement positions within a sticker placer is dependent upon the
maximum course length and required spacing between stickers. Most
multistation sticker placers operate the various positions simultaneously,
wherein a number of stickers are placed in spaced apart relationship with
one another along the length of the course of lumber.
A number of problems attend the use of conventional sticker placer
apparatus. Most have to do with the imperfections frequently found in the
stickers themselves, which are manufactured cheaply and are continuously
recycled. With normal use, stickers tend to bow, twist, crook, wear and
flatten as a result of being pressed between courses of lumber of varying
thickness, and as a result of handling and weathering. In some cases, the
thinnest sticker approaches half the thickness of the thickest sticker.
Stickers also may be oversized in thickness from improper manufacture, or
may be of varying surface conditions from improper screening or grading.
Conventional sticker placer apparatus store stickers in sticker feed
pockets, or magazines, one atop the other with the greater cross-sectional
dimension oriented horizontally. In order to eject or release the bottom
sticker in a feed pocket, conventional placers either pinch the edge of
the second sticker from the bottom of the pocket, while permitting the
bottom sticker to drop free, or provide a throat, in the side of the
pocket's base, large enough for a single sticker to be ejected sideways
through, yet small enough to prevent the ejection of more than one.
The former type of sticker placer, commonly known as a pinching sticker
placer, suffers the drawback that the second sticker from the bottom
precisely must be located and shaped in the area of the pinching mechanism
to prevent its falling. Thus, if the second sticker is too high or too low
because the bottom sticker is too thick, too thin, twisted or bowed, the
pinching mechanism cannot pinch it properly and keep it from falling.
Similarly, if the edge of the second sticker is not both planar and
vertical in the area of the pinching mechanism, the mechanism may be
incapable of preventing its falling.
The latter type of sticker placer, commonly known as a side ejection
sticker placer, easily may jam when two thin stickers find their way to
the bottom of the feed pocket and both attempt to pass simultaneously
through the opening. Similarly, if the bottom sticker is oversized in
thickness or twisted or bowed, it may not pass through the opening.
Finally, the surface condition of one or both of the bottom stickers in
the feed pocket may prevent their sliding smoothly across one another,
resulting thereby in a jammed sticker placer.
Other problems arise when a conventional sticker placer is used with
courses of lumber that, when stacked, are uneven (nonplanar) or unlevel.
Typically, a multi-station sticker placer positively links together the
reciprocating motion of its placement arms. All arms descend for a
predetermined period of time or until the earliest stop is reached, and
then all arms simultaneously halt their descent, regardless of whether all
arms have reached the level of the top of the course of lumber. As all
stickers then are released simultaneously, some therefore are not
controllably placed, but rather are dropped onto the course of lumber.
Furthermore, if one arm of a multi-position sticker placer should jam,
none is allowed to operate, because the movement of the common link
mechanism is stopped. Similar problems arise with those side ejection
sticker placers that eject stickers from multiple positions simultaneously
through a positive link drive. Once again, if an individual sticker
ejector jams, the movement of the common link is stopped, and none of the
stickers is ejected.
It is desirable to provide an improved sticker placer that overcomes the
problems described above. Specifically, the sticker placer should be
highly tolerant of the inevitable sticker misfits, and should be virtually
jam-proof. Such a sticker placer would be capable of fully automatic,
repeatably accurate and rapid placement of multiple stickers atop
consecutive courses of lumber, which may be not precisely level or planar.
The improved sticker placer should operate reliably under extreme
environmental conditions of dust and humidity.
Accordingly, it is a principal object of the present invention to provide a
multi-position sticker placer having significantly improved placement
accuracy, throughput and reliability.
Another object of the invention is to provide such apparatus that is
compatible with automatic loading of the sticker feed pockets.
Yet another object of the present invention is to provide a sticker placer
that optimizes the path traversed by a sticker between horizontal
conveyance and vertical placement.
A further object of the invention is to provide a virtually jam-proof,
multi-position sticker placer.
Still another object of the invention is to provide such apparatus with a
minimum number of drive mechanisms.
Another important object is to provide multi-position apparatus that
permits the selective disabling of individual
The apparatus of the present invention takes the form of a stationary,
frame-mounted apparatus including multiple, gravity-fed inclined sticker
feed pockets, each of which feeds edge-abutted stickers to a vertically
reciprocable placement arm. Selectively, each placement arm alternately
may be lowered and raised by a slider link, or roller chain, that
adjustably is extended and retracted by a single, hydraulic or pneumatic
cylinder common to all arms. It will be understood that slider link, as
used herein, describes the fact that the link is permitted to slip, or
disengage individual arms from the common drive cylinder during the
extension thereof, thus distinguishing positive links that rigidly connect
members for one-to-one movement therebetween.
Each placement arm is equipped with dual, positive sticker capture means
including a pivotable, generally horizontal cradle and releasable sticker
retaining means, which impinge, throughout the placement cycle, on the
sticker's upper face. Plural stops halt each arm's descent when the top of
the lumber course is reached thereby, causing the roller chain to slacken
until fully extended. The resulting lost motion beneficially provides a
dwell time during which a spring tensioned rocker arm, to which the roller
chain is attached, may pivot the support arm out from under the sticker.
During this dwell time, the sticker retaining means continues to urge the
sticker downwardly, thus accurately and securely positioning it atop the
course of lumber. Pivoting of the rocker arm, made possible by the
slackening of the roller chain when at least one of the placement arm's
stops reaches the top of the lumber course, also positions the roller
chain on the opposite side of the rocker arm's pivotal axis so that, upon
retraction of the roller chain, the support arm is maintained in its
pivoted, sticker releasing position as the placement arm is raised and the
placement cycle is completed.
The to-be-placed sticker immediately upstream from the sticker being placed
is retained, throughout the placement cycle just described, by an
adjustable, spring tensioned pinch bar that impinges upon the to-be-placed
sticker's upper face until the placement arm completes its upstroke. Thus,
by the orientation of the stickers in edge, rather than face abutment, and
by the positive retention of upstream stickers within the feed pocket,
stickers smoothly, controllably advance toward the placement arm.
Feed gates are provided adjacent the top of each feed pocket. Controlled
opening and closing of the feed gates and the use of a conventional
conveyor, preferably loading chains, provide uninterrupted, fully
automatic operation of the sticker placer apparatus.
Thus, the objects of the invention are realized. Stickers are handled
within the inclined feed pocket in edge-to-edge, rather than face-to-face,
orientation, which renders them more controllable despite surface
irregularities, over- or under-sizing, bowing, twisting or crooking. By
the positive capture of each sticker by its opposing faces, rather than
opposing edges, placement accuracy is greatly improved. Inherently
unreliable timing circuits and limit switches are avoided by the use of
placement arm-mounted stops, spring tensioned rotation and a slider link,
which provide dwell time between the down- and up-strokes for the
time-critical release of the sticker. Lost motion provided by the stops,
the variable tension slider link and the common drive cylinder enable each
placement arm to `float` to the level of the lumber at its position along
the length of the lumber course, and permit other placement arms to
continue to operate in the event one or more jams. A selectively operable
feed gate at the top of each feed pocket provides an uninterrupted supply
of stickers, based upon the demand at each placement position, for the
fully automatic operation of the sticker placer.
These and other objects and advantages of the invention will become more
fully apparent when the detailed description below is read with reference
to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevation of a sticker placer apparatus made in accordance
with the invention, showing its use with conventional lumber
stacking/indexing equipment.
FIG. 2 is a fragmentary, side elevation of the placer apparatus.
FIG. 3 is a front elevation showing one of the placer's placement carriages
in a raised position (solid lines), and in a lowered position (dashed
lines).
FIG. 4 is an enlarged, fragmentary, cross-sectional view taken generally
along the lines 4--4 in FIG. 3.
FIG. 5 is an enlarged, fragmentary, side elevation taken generally along
the lines 5--5 in FIG. 3, showing a placement arm in its lowered, sticker
capture position.
FIG. 6 is an enlarged, fragmentary, cross-sectional view similar to FIG. 5,
but showing the placement arm in its sticker release
FIG. 7 is an enlarged, fragmentary, side elevation taken generally along
the lines 7--7 in FIG. 3.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 may be thought of as a general system diagram, showing, in side
elevation, the sticker placer of the present invention, indicated
generally at 20, mounted on stationary frame 22 above conventional lumber
stacker equipment, indicated generally at 24. Lumber courses 26 are
generally horizontally supported by lumber stacker 24 and it is understood
by those skilled in the art that, as each new course of lumber is
developed for stacking thereabove, stacker 24 indexes, or advances,
downwardly in order to maintain an approximately consistent height of the
top 26a of the lumber course on which the next array of stickers, such as
stickers 28, may be placed. Stickers 28 are placed by sticker placer 20 at
predetermined, longitudinally spaced apart positions along top lumber
course 26, and are oriented generally transverse thereto.
Referring still to FIG. 1, sticker placer apparatus 20 includes, in the
preferred embodiment, continuous-loop, horizontal conveyor means or
loading chains 30, having feed dogs (not shown in FIG. 1, but shown in
FIG. 2 at 38) spaced therealong. By advancing in the direction indicated
by the arrows, conveyor means 30 ensures a continuous supply of stickers
for placement at selective positions along the top 26a of the course of
lumber. Independently, selectively operable feed gates, such as gates 32,
may be driven open to receive into sticker receiving means, or a
corresponding magazine, or sticker feed pocket, such as pocket 34,
stickers as they otherwise endlessly traverse conveyor means 30. A full
supply of stickers may thus be maintained in each of the pockets 34.
Turning now to FIG. 2, sticker placer 20 is shown in an enlarged,
fragmentary side elevation, and will be described in the sequence of its
normal operation. A feed dog 38 connected to conveyor 30 urges a sticker
28 toward open feed gate 32. Sticker 28, generally having opposite faces
28a, 28b and opposite edges 28c, 28d, is shown in end view as it slides
generally longitudinally horizontally along a horizontal stretch 34a of
feed pocket 34. With feed gate 32 open, sticker pocket 34 will receive
sticker 28 between parallel, spaced apart upper rail 40 and lower rail 42.
Sticker 28 will slide on its lower face 28a, under the force of gravity,
along lower rail 42 towards the mouth 44 of pocket 34. In the illustration
of FIG. 2, sticker 28 will become the sticker furthest upstream in pocket
34, i.e. the sticker furthest from mouth 44 and closest to feed gate 32.
Ultimately, sticker 28 will come to rest against a downstream sticker,
with leading edge 28c engaging the trailing edge of that sticker within
pocket 34. Each pocket 34 consists of a pair of laterally spaced apart
rails 40, 42. For each pocket 34 shown in FIG. 2, there may be one or more
provided aligned therewith in a direction extending transversely of the
apparatus as seen in FIG. 3.
Importantly, pocket 34 is inclined, at an angle preferably between
30.degree. and 60.degree., and most preferably at an angle of
approximately 45.degree., relative to conveyor means 30, and rails 42 are
made of smoothly finished, tubular steel, thereby promoting the smooth
sliding of stickers generally longitudinally horizontally down the incline
and transverse thereto. A substantial advantage is obtained thereby, as a
sticker, such as 28, need not change direction as abruptly as it might
were pocket 34 generally vertically oriented, as is customary.
It is equally important that stickers, such as 28, within pocket 34 are
edge-stacked, rather than being stacked face-to-face. By their novel
arrangement within pocket 34, the inherent tendency of the stickers to bow
or twist least impacts the ability of pocket 34 to maintain their
consistent, stacked orientation. The handling of stickers by their faces,
throughout conveyance, stacking and placement, renders sticker placer 20
substantially more tolerant of inherent sticker imperfections, as sticker
faces typically are more regular than sticker edges.
Finally, it is important to note that the distance between upper and lower
rails 40, 42 (in a direction perpendicular thereto) is dimensioned to be
substantially greater than the nominal, predetermined thickness of the
stickers which will pass therebetween. This cooperative arrangement of
rails 40, 42 ensures the controlled, gravity-fed, sliding advancement of
stickers, such as 28, toward mouth 44 for placement, despite the
frequently oversized or twisted condition of recycled stickers.
Referring still to FIG. 2, it will be seen that associated with mouth 44 of
pocket 34, and operable with placement arm 36, is releasable sticker
retention means, or a pinch bar mechanism, indicated generally at 46.
Pinch bar mechanism 46 includes a pinch bar 48, shown impinging upon the
upper face 50b of to-be-placed sticker 50. In a manner that will be
described, pinch bar 8 so impinges under spring tension throughout the
downstroke of placement arm 36b and through most of the upstroke thereof,
with pinch bar 48 being lifted at the end of the upstroke to release
to-be-placed sticker 50 for placement. It may be seen that to-be-placed
sticker 50, thus retained at mouth 44 of pocket 34, prevents the further
downward sliding of upstream stickers, such as sticker 52, by the
edge-lengthwise abutment therebetween.
Positive sticker capture means, or a sticker capture mechanism, is
indicated generally at 54. In the preferred embodiment, a
sticker-being-placed 56 is cradled, during the downstroke of placement arm
36b, above dual, laterally spaced apart, generally horizontal, pivotable
support arms 58, of which one is shown in FIG. 2 in its sticker release
position (the other arm transversely aligned with the arm 58 shown in FIG.
2 appears in FIG. 3). With placement arm 36b in the lowered position, as
illustrated in FIG. 2, sticker-being-placed 56 is urged downwardly onto
the top 26a of the course of lumber by impingement upon its upper face 56b
of dual, corresponding, laterally spaced apart, pivotable pincer arms,
such as pincer arm 60. A support arm 58 and its cooperating pincer arm 60
make up what is referred to herein as a capture means or mechanism 54.
Sticker 56 controllably and generally vertically may be displaced from
mouth 44 of pocket 34 to the top 26a of lumber course 26 by capture
mechanism 54, rather than prematurely being released or dropped. Although
the preferred embodiment is seen to include dual, symmetric sticker
capture mechanisms, it will be appreciated that, within the spirit of the
invention, sticker capture means 54 may comprise a single, pivotable
support arm and a corresponding releasable sticker retainer capable of
urging the sticker into captured engagement therewith.
Importantly, each individual placement arm such as arms 36a, 36b, 36c, may,
by the novel slider link mechanism to be described below, `seek`, or
`float to`, the level of the top 26a of the course of lumber at their
individual positions therealong. Even if the lumber course is unlevel or
of variable height as it extends longitudinally beneath sticker placer 20,
nevertheless all stickers placed thereby during a placement cycle will be
placed positively at the various levels along lumber course 26. This
improved operation is illustrated in FIG. 2, wherein arm 36c has reached a
lower position of the lumber therebeneath than have arms 36a, 36b, 36d,
which are positioned at their higher, respective lumber heights. This
represents a substantial improvement over previously state-of-the-art
apparatus, in which positive link means connecting adjacent placement arms
permit the downstroke of any given placement arm to
terminate--prematurely, in the event that the arm is positioned over a
slightly depressed length of lumber--at a predetermined time after the
downstroke begins, or at a predetermined height where the reciprocal reach
of the drive mechanism is exhausted.
The novel slider link mechanism of the present invention serves another
important purpose: dwell time is provided between the downstroke and the
upstroke of each placement cycle, during which time support arm 58 may be
pivoted from a first, sticker supporting position to a second, sticker
release position.
The advantages described immediately above are provided by sticker
displacing means that includes slider link extending and retracting means
that, in the preferred embodiment, takes the form of a single, common,
reciprocable drive cylinder 62 that is positively, or strongly,
reciprocally linked to a horizontal actuator 64. Actuator 64 is weakly
linked, in turn, to a variable tension link mechanism, indicated generally
at 66. Link mechanism 66 transforms the generally horizontal, reciprocal
motion of actuator 64 within channels 65 into the generally vertical,
reciprocal motion of placement arm 36 and a range of lost motion
sufficient to provide the important dwell time associated with capture
mechanism 54.
FIG. 3 is a front elevation corresponding to FIG. 2, in which the laterally
spaced apart features of sticker placer 20 are illustrated. within bar
guard 70. Carriage bar 68 of a placement arm means 36 is vertically
reciprocatable It is guided along its generally vertical path by an upper
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